202duinoで正弦波 → ノイズがのる → ATtiny412でDAC使用

ATtiny202で正弦波をつくってみたんだけど、おそらく慣れないPWMの操作に問題があると思われ、ノイズがのってしまいました。

//  megaTinyCore ATtiny202/212/402/412 Sine Wave
static const uint16_t OCTAVE9[] = { 7023, 7441, 7883, 8352, 8848, 9375, 9932, 10523,11148,11811,12513,13258 };
static const uint8_t  SINE256[] = {
    0,  0,  0,  0,  1,  1,  1,  2,  2,  3,  4,  5,  5,  6,  7,  9,  10, 11, 12, 14, 15, 17, 18, 20, 21, 23, 25, 27, 29, 31, 33, 35,
   37, 40, 42, 44, 47, 49, 52, 54, 57, 59, 62, 65, 67, 70, 73, 76,  79, 82, 85, 88, 90, 93, 97,100,103,106,109,112,115,118,121,124,
  128,131,134,137,140,143,146,149,152,155,158,162,165,167,170,173, 176,179,182,185,188,190,193,196,198,201,203,206,208,211,213,215,
  218,220,222,224,226,228,230,232,234,235,237,238,240,241,243,244, 245,246,248,249,250,250,251,252,253,253,254,254,254,255,255,255,
  255,255,255,255,254,254,254,253,253,252,251,250,250,249,248,246, 245,244,243,241,240,238,237,235,234,232,230,228,226,224,222,220,
  218,215,213,211,208,206,203,201,198,196,193,190,188,185,182,179, 176,173,170,167,165,162,158,155,152,149,146,143,140,137,134,131,
  128,124,121,118,115,112,109,106,103,100, 97, 93, 90, 88, 85, 82,  79, 76, 73, 70, 67, 65, 62, 59, 57, 54, 52, 49, 47, 44, 42, 40,
   37, 35, 33, 31, 29, 27, 25, 23, 21, 20, 18, 17, 15, 14, 12, 11,  10,  9,  7,  6,  5,  5,  4,  3,  2,  2,  1,  1,  1,  0,  0,  0 };

void setup(){                   // Register Settings
  TCB0.CTRLA = TCB_CLKSEL_CLKDIV1_gc | TCB_ENABLE_bm;   // 20MHz / 1 / 256 -> 78,125Hz
  TCB0.CTRLB = TCB_CNTMODE_PWM8_gc   | TCB_CCMPEN_bm;   // 8-Bit PWM mode, Output Enable (WO,PA6,megaTinyCore:P0)
  TCB0.CCMPL = 0xff;                                    // top value = 255
  TCB0.CCMPH = 0;                                       // output value
}

void loop(){
  sineWave( 60,  500);          // C4
  sineWave( 64,  500);          // E4
  sineWave( 67,  500);          // G4
  sineWave( 72, 2000);          // C5
  delay(1000);
}

void sineWave(uint8_t midiNum, uint16_t msDuration) {
  uint16_t i, di = OCTAVE9[ midiNum % 12 ] >> (10 - midiNum / 12);  // 256 times the Wave Table subscript to advance in one cycle
  uint32_t cycDuration = F_CPU / 256 / 1000 * msDuration;           // Convert duration to number of cycles
  do {
    TCB0.CCMPH = SINE256[ ( (i += di) >> 8 ) ];         // 8bit PWM (78,125Hz)
    while( !TCB0.INTFLAGS );                            // Waiting for TCB0 overflow (every 12.8usec(78,125Hz))
    TCB0.INTFLAGS = TCB_CAPT_bm;                        // cleared by writing a '1'
  } while( --cycDuration );                             // Exit if note data is 0
  TCB0.CCMPH = 0;                                       // Set output to 0
}

そこで、tinyAVR 1-Series の ATtiny412 を使用した「202duino w/ ATtiny412」でDACを使ってみることにしました。
せっかくなので正弦波のサンプリングも4倍にしたりしてみました。

//  megaTinyCore ATtiny202/212/402/412 Sine Wave
static const uint32_t OCTAVE9[] = { 460256562,487624841,516620523,547340378,579886931,614368802,650901072,689605664,730611750,774056186,820083962,868848692 };
static const uint8_t SINE1024[] = {
  0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,1,1,1,1,1,1,1,1,2,2,2,2,2,2,2,3,3,3,3,3,4,4,4,4,4,5,5,5,5,5,6,6,6,6,7,7,7,8,8,8,8,9,9,
  9,10,10,10,10,11,11,11,12,12,12,13,13,14,14,14,15,15,15,16,16,17,17,17,18,18,19,19,19,20,20,21,21,22,22,22,23,23,24,24,25,25,26,
  26,27,27,28,28,29,29,30,30,31,31,32,32,33,33,34,34,35,35,36,36,37,38,38,39,39,40,40,41,42,42,43,43,44,44,45,46,46,47,48,48,49,49,
  50,51,51,52,53,53,54,54,55,56,56,57,58,58,59,60,60,61,62,62,63,64,64,65,66,66,67,68,69,69,70,71,71,72,73,73,74,75,76,76,77,78,79,
  79,80,81,81,82,83,84,84,85,86,87,87,88,89,90,90,91,92,93,93,94,95,96,96,97,98,99,99,100,101,102,103,103,104,105,106,106,107,108,
  109,109,110,111,112,113,113,114,115,116,117,117,118,119,120,120,121,122,123,124,124,125,126,127,128,128,129,130,131,131,132,133,
  134,135,135,136,137,138,138,139,140,141,142,142,143,144,145,146,146,147,148,149,149,150,151,152,152,153,154,155,156,156,157,158,
  159,159,160,161,162,162,163,164,165,165,166,167,168,168,169,170,171,171,172,173,174,174,175,176,176,177,178,179,179,180,181,182,
  182,183,184,184,185,186,186,187,188,189,189,190,191,191,192,193,193,194,195,195,196,197,197,198,199,199,200,201,201,202,202,203,
  204,204,205,206,206,207,207,208,209,209,210,211,211,212,212,213,213,214,215,215,216,216,217,217,218,219,219,220,220,221,221,222,
  222,223,223,224,224,225,225,226,226,227,227,228,228,229,229,230,230,231,231,232,232,233,233,233,234,234,235,235,236,236,236,237,
  237,238,238,238,239,239,240,240,240,241,241,241,242,242,243,243,243,244,244,244,245,245,245,245,246,246,246,247,247,247,247,248,
  248,248,249,249,249,249,250,250,250,250,250,251,251,251,251,251,252,252,252,252,252,253,253,253,253,253,253,253,254,254,254,254,
  254,254,254,254,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,
  255,255,255,255,255,255,255,255,255,255,255,255,255,254,254,254,254,254,254,254,254,253,253,253,253,253,253,253,252,252,252,252,
  252,251,251,251,251,251,250,250,250,250,250,249,249,249,249,248,248,248,247,247,247,247,246,246,246,245,245,245,245,244,244,244,
  243,243,243,242,242,241,241,241,240,240,240,239,239,238,238,238,237,237,236,236,236,235,235,234,234,233,233,233,232,232,231,231,
  230,230,229,229,228,228,227,227,226,226,225,225,224,224,223,223,222,222,221,221,220,220,219,219,218,217,217,216,216,215,215,214,
  213,213,212,212,211,211,210,209,209,208,207,207,206,206,205,204,204,203,202,202,201,201,200,199,199,198,197,197,196,195,195,194,
  193,193,192,191,191,190,189,189,188,187,186,186,185,184,184,183,182,182,181,180,179,179,178,177,176,176,175,174,174,173,172,171,
  171,170,169,168,168,167,166,165,165,164,163,162,162,161,160,159,159,158,157,156,156,155,154,153,152,152,151,150,149,149,148,147,
  146,146,145,144,143,142,142,141,140,139,138,138,137,136,135,135,134,133,132,131,131,130,129,128,128,127,126,125,124,124,123,122,
  121,120,120,119,118,117,117,116,115,114,113,113,112,111,110,109,109,108,107,106,106,105,104,103,103,102,101,100,99,99,98,97,96,96,
  95,94,93,93,92,91,90,90,89,88,87,87,86,85,84,84,83,82,81,81,80,79,79,78,77,76,76,75,74,73,73,72,71,71,70,69,69,68,67,66,66,65,64,
  64,63,62,62,61,60,60,59,58,58,57,56,56,55,54,54,53,53,52,51,51,50,49,49,48,48,47,46,46,45,44,44,43,43,42,42,41,40,40,39,39,38,38,
  37,36,36,35,35,34,34,33,33,32,32,31,31,30,30,29,29,28,28,27,27,26,26,25,25,24,24,23,23,22,22,22,21,21,20,20,19,19,19,18,18,17,17,
  17,16,16,15,15,15,14,14,14,13,13,12,12,12,11,11,11,10,10,10,10,9,9,9,8,8,8,8,7,7,7,6,6,6,6,5,5,5,5,5,4,4,4,4,4,3,3,3,3,3,2,2,2,2,
  2,2,2,1,1,1,1,1,1,1,1,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0 };

void setup(){                   // Register Settings
  TCB0.CTRLA = TCB_CLKSEL_CLKDIV1_gc | TCB_ENABLE_bm;   // 20MHz / 1 / 256 -> 78,125Hz
  TCB0.CTRLB = TCB_CNTMODE_PWM8_gc   | TCB_CCMPEN_bm;   // 8-Bit PWM mode, Output Enable (WO,PA6,megaTinyCore:P0)
  TCB0.CCMPL = 0xff;                                    // top value = 255
  TCB0.CCMPH = 0;                                       // output value
  #ifdef DAC0
  VREF.CTRLA |= VREF_DAC0REFSEL_4V34_gc;                // Voltage reference at 4.34V
  VREF.CTRLB |= VREF_DAC0REFEN_bm;                      // DAC0/AC0 reference enable: enabled
  delayMicroseconds(25);                                // Wait VREF start-up time
  PORTA.PIN6CTRL &= ~PORT_ISC_gm;                       // Disable digital input buffer
  PORTA.PIN6CTRL |=  PORT_ISC_INPUT_DISABLE_gc;          
  PORTA.PIN6CTRL &= ~PORT_PULLUPEN_bm;                  // Disable pull-up resistor
  DAC0.CTRLA = DAC_ENABLE_bm | DAC_OUTEN_bm;            // Enable DAC, Output Buffer
  #endif
  }

void loop(){
  sineWave( 60,  500);          // C4
  sineWave( 64,  500);          // E4
  sineWave( 67,  500);          // G4
  sineWave( 72, 2000);          // C5
  delay(1000);
}

void sineWave(uint8_t midiNum, uint16_t msDuration){
  uint32_t i, di, cycDuration;
  di = OCTAVE9[ midiNum % 12 ] >> (10 - midiNum / 12);  // 2^22 times the Wave Table subscript to advance in one cycle
  cycDuration = F_CPU / 256 / 1000 * msDuration;        // Convert duration to number of cycles
  do {
    #ifdef DAC0
    DAC0.DATA  = SINE1024[ ( (i += di) >> 22 ) ];       // 8bit DAC
    #else
    TCB0.CCMPH = SINE1024[ ( (i += di) >> 22 ) ];       // 8bit PWM (78,125Hz)
    #endif
    while( !TCB0.INTFLAGS );                            // Waiting for TCB0 overflow (every 12.8usec(78,125Hz))
    TCB0.INTFLAGS = TCB_CAPT_bm;                        // cleared by writing a '1'
  } while( --cycDuration );                             // Exit if data is 0
  #ifdef DAC0
  DAC0.DATA  = 0;                                       // Set output to 0
  #endif
  TCB0.CCMPH = 0;                                       // Set output to 0
}

（DACについての参考）
Getting Started with Digital-to-Analog Converter (DAC) - TB3210
http://ww1.microchip.com/downloads/en/Appnotes/TB3210-Getting-Started-with-DAC-DS-90003210.pdf

タグ：音 正弦波 DAC ATtiny412 ATtiny202 202duino